site:edaboard.com vector voltmeter

Some years ago HP sold a one port impedance meter that went up to 110 MHz. It was all analog with two analog meters showing magnitude and phase. The frequency was set with a range switch and rotary knob.

What was the model number of this instrument?

Maybe you're thinking of the HP8405A Vector Voltmeter? Freq range is 1 to 1000 MHz.

http://www.atecorp.com/Equipment/HP/8405A.htm

It is not the voltmeter I want. The instrument had a single probe and a hole in the front panel with a 50 ohm load. The probe would mate with this hole to calibrate the instrument. The 4193A was a subsequent all digital version.